National Center for Complementary and Integrative Health (NCCIH)

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Evening Primrose Oil

Common Names: 
evening primrose oil, EPO
Latin Name: 
Oenothera biennis


Evening Primrose

© Steven Foster

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This fact sheet provides basic information about evening primrose oil—common names, what the science says, potential side effects and cautions, and resources for more information.

Evening primrose is a plant native to North America, but it grows in Europe and parts of the Southern hemisphere as well. It has yellow flowers that bloom in the evening. Evening primrose oil contains the fatty acid gamma-linolenic acid (GLA).

Evening primrose oil has been used since the 1930s as a folk or traditional remedy for eczema (a condition in which the skin becomes inflamed, itchy, or scaly because of allergies or other irritation). More recent folk uses include other conditions involving inflammation, such as rheumatoid arthritis; conditions affecting women’s health, such as breast pain associated with the menstrual cycle, menopausal symptoms, and premenstrual syndrome (PMS); cancer; and diabetes.

Evening primrose oil is extracted from the seeds of the evening primrose. The oil is usually put into capsules for use.


What the Science Says

  • There is not enough evidence to support the use of evening primrose oil for any health condition.
  • According to a comprehensive 2013 evaluation of the evidence, evening primrose oil, taken orally (by mouth), is not helpful for relieving symptoms of eczema.
  • Evening primrose oil has been studied for rheumatoid arthritis and breast pain. However, study results are mixed, and most studies have been small and not well designed.
  • Evening primrose oil does not appear to affect menopausal symptoms.
  • The best-designed clinical trials of evening primrose oil for PMS found no effect.


Side Effects and Cautions

  • Evening primrose oil is well tolerated by most people, when taken for short periods of time. Mild side effects include gastrointestinal upset and headache.
  • The safety of long-term use of evening primrose oil has not been established.
  • Evening primrose oil may increase bleeding in people who are taking the anticoagulant (blood thinning) medication warfarin.
  • Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.


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The NCCIH Clearinghouse provides information on NCCIH and complementary and integrative health approaches, including publications and searches of Federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.

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Office of Dietary Supplements (ODS), National Institutes of Health (NIH)

ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public. Its resources include publications (such as Dietary Supplements: What You Need to Know), fact sheets on a variety of specific supplement ingredients and products (such as vitamin D and multivitamin/mineral supplements), and the PubMed Dietary Supplement Subset.


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Key References

  • Bamford JTM, Ray S, Musekiwa A, et al. Oral evening primrose oil and borage oil for eczema. Cochrane Database of Systematic Reviews. 2013; (4):CD004416. Accessed at on May 7, 2013.
  • Evening primrose oil. Natural Medicines Comprehensive Database Web site. Accessed at on June 11, 2009.
  • Evening primrose oil (Oenothera biennis L.). Natural Standard Web site. Accessed at on June 11, 2009.
  • Shahidi F, Miraliakbari H. Evening primrose (Oenothera biennis). In: Coates P, Blackman M, Cragg G, et al., eds. Encyclopedia of Dietary Supplements. New York, NY: Marcel Dekker; 2005:197–210.


This publication is not copyrighted and is in the public domain. Duplication is encouraged.

NCCIH has provided this material for your information. It is not intended to substitute for the medical expertise and advice of your primary health care provider. We encourage you to discuss any decisions about treatment or care with your health care provider. The mention of any product, service, or therapy is not an endorsement by NCCIH.

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NCCIH Publication No.: 
December 2006
May 2013